For beginning calorie counters, MyFitnessPal is a free food-logging app that lets you track calories and set custom goals for macros and micros, making it ideal for people with goals other than simply to eat "less calories."

Fitocracy makes fitness fun with free workouts that whip you into shape using your own custom plan designed with the company's extensive workout database. The app also turns workouts into a game by offering points for each successful completion.

Strava is a running/cycling log, a tracking app and a fitness community all in one. Its ace in the hole is its near-universal compatibility with devices and services, including ones from Garmin, TomTom, Polar, Fitbit, Timex, Suunto, and more.

If you have more than seven minutes, Nike+ Training Club is a free app with over 100 workouts of varying difficulties, time constraints, and equipment requirements, led by Nike Master Trainers. The app even lets you choose your own playlist.